(Meth)acrylate ester compounds having cyclic propylene carbonate groups are described in Decker, C., et al, Makromol. Chem, Rapid Commun, 11, 159-167 (1990); Decker, C., et al, Cpt. 2 of Vol. III xe2x80x9cRadiation Curing in Polymer Science and Technology,xe2x80x9d Fouassier et al, eds, Elsevier Applied Science, NY (1993); Jansen, et al, Polymer Preprints, 42(2), 769 (2001); U.S. Pat. No. 5,621,119; U.S. Pat. No. 6,001,535; European Patent No. EP 0 001 088; European Pat. No. EP 0 667 560; and International Patent Publication No. WO 02/42383. Such compounds have advantages in radiation curing compositions, for instance, for their high cure rates and improved hardness and flexibility properties.
A variety of different linking structures between the (meth)acrylate ester group and the cyclic propylene carbonate groups are described in the documents listed above. However, it has not previously been proposed to prepare such compounds with acetal or hemiacetal ester moieties in the linking structure.
The present invention is directed to novel acetal or hemiacetal ester linked propylene carbonate functional (meth)acrylic esters, and to methods for their synthesis.
The inventive compounds are characterized by the formula: 
where
R1is H or methyl,
R2 is H or alkyl,
each R3, independently, is a C2-C4 alkylene,
n is 0-4,
nxe2x80x2 is 1-4,
x is one or more,
y is one or more,
x+y=z, and
A is a z-valent organic group linked to the group(s) on the left thereof through a carbon atom thereof and linked to the group(s) on the right thereof through an ether or ester oxygen atom, or, provided that x and y are both 1, is a direct bond.
The inventive compounds may be readily synthesized by reaction of certain alk-1-enyl alkylene cyclocarbonate ethers and known (meth)acrylic carboxylic acids or hydroxy functional (meth)acrylic esters. In addition to providing compounds having a single (meth)acrylate and a plurality of cyclic propylene carbonate groups, the method is readily adaptable to preparation of compounds having a each of these functionalities, but with one or the other, or both, being present in a plurality.
All published documents, including all U.S. patent documents, mentioned anywhere in this application are hereby expressly incorporated herein by reference in their entirety. Any copending patent applications, mentioned anywhere in this application are also hereby expressly incorporated herein by reference in their entirety.
Alk-1-enyl alkylene cyclocarbonate ethers of the formula: 
where R2, R3, n and nxe2x80x2 are as previously defined, are known, for instance from WO 92/04383. Such alk-1-eneyl ethers may be reacted with (meth)acrylic carboxylic acids or hydroxy functional (meth)acrylic esters to produce the compounds of the invention.
In formula I above, the z-valent organic group A may be for instance an alkylene group, such as ethylene, propylene and butylene; a group of the formula xe2x80x94(R3O)nxe2x80x3xe2x80x94, where R3 is as previously defined and nxe2x80x3 is as defined for n; an alkyleneacetyloxy group. The group A may also be a residue of any other partially (meth)acrylated polyol, for instance the glycerol residue of glyceryl monoacrylate or of glyceryl diacrylate.
Examples of suitable R2 groups include H, and methyl, ethyl, n-propyl, isopropyl, butyl, cyclohexyl, hexyl, phenyl, octyl, 2-ethylhexyl, decyl, lauryl, cetyl and octadecyl. In some embodiments R2 may be H or an alkyl group of 1-10 carbon atoms, especially H (i.e. a vinyl ether), or methyl (i.e. a propenyl ether).
Examples of R3 groups include ethylene, 1,2-propylene, 1,3-propylene, 1,4-butylene and 1,2-butylene.
Specific useful ether compounds which may be employed in such synthesis reactions are prop-1-enyl propylene carbonate (PEPC), and the vinyloxyethyl ether of propylene carbonate.
Useful (meth)acrylic carboxylic acids which may be employed in such synthesis reactions include acrylic acid, methacrylic acid, B-carboxyethyl acrylate and B-carboxyethyl methacrylate.
Useful (meth)acrylic hydroxy esters which may be employed in such synthesis reactions are partially (meth)acrylated diols and polyols. Examples of such compounds include hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, glyceryl monomethacrylate, glyceryl monoacrylate, glyceryl dimethacrylate, glyceryl diacrylate, trimethylol propane monomethacrylate, trimethylol propane monomethacrylate, trimethylol diacrylate, trimethylol propane dimethacrylate; pentaerythritol tri(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol mono(meth)acrylate, sorbitol penta(meth)acrylate, sorbitol tetra(meth)acrylate, sorbitol tri(meth)acrylate, sorbitol di(meth)acrylate, sorbitol mono(meth)acrylate, hydroxy functional saccharide (meth)acrylates, diethylene glycol mono(meth)acrylate, poly(ethylene glycol) mono(meth)acrylate, dipropylene glycol mono(meth)acrylate; poly(propylene glycol) mono(meth)acrylate, and the like.
The reaction of the alk-1-enyl alkylene cyclocarbonate ethers with the (meth)acrylic carboxylic acids and/or (meth)acrylic hydroxy esters is a simple thermally driven addition across the alk-1-enyl double bond. Addition of a hydroxyalkyl (meth)acrylate to a compound of formula II above, produces an acetal linked propylene carbonate functional (meth)acrylic ester, whereas addition of a (meth)acrylic acid compound produces a hemiacetal linked propylene carbonate functional (meth)acrylic ester. The addition reactions are run at elevated temperature, suitably a temperature range 20-120xc2x0 C., preferably below 100xc2x0 C. and above 50xc2x0 C., and especially at about 70-90xc2x0 C. for a time of 1-12 hours. Advantageously, the hydroxy ester or carboxylic acid is added to the compound of formula II incrementally. Typically a stabilizer is added to prevent premature polymerization. In certain cases it may be advantageous to employ an acidic catalyst such as para-toluene sulfonic acid or phosphoric acid to increase the reaction rates or to drive the reaction to completion.
In general, a suitable work-up procedure involves washing or treating the crude reaction mixture with sodium bicarbonate solution to remove residual acids (reagent and catalyst) if present, followed by washing with water to remove ionic impurities, drying with a suitable desiccant and filtering to remove insoluble particulate contaminants. In certain cases it may be desirable to vacuum strip the crude product and in some cases to distill or precipitate the monomers from blends of solvents and non-solvents. In other cases, chromatographic separation may be appropriate, particularly where isolation of highly purified material is required.
In an alternate synthesis, alk-1-enyl alkyleneepoxy ether compounds, for instance vinyl glycidyl ether or 1-propenyl glycidyl ether, may be first reacted with a hydroxyalkyl (meth)acrylate or a (meth)acrylic acid compound, to produce an acetal linked epoxy functional (meth)acrylic ester or a hemiacetal linked epoxy functional (meth)acrylic ester, respectively. Such products may then be reacted with carbon dioxide to form the desired propylene carbonate compound of the invention.
The inventive compounds are illustrated by the following:
Reaction product of propylene ether of propylene carbonate (PEPC) and acrylic acid: 
Reaction product of vinyloxyethyl ether of propylene carbonate and acrylic acid 
Reaction product of PEPC and xcex2-carboxyethyl acrylate: 
Reaction product of vinyloxyethyl ether of propylene carbonate and 2-hydroxyethyl acrylate: 
Reaction product of PEPC and 2-hydroxyethyl acrylate: 
Reaction product of PEPC and glycerol dimethacrylate: 
Reaction product of PEPC and glycerol monomethacrylate: 
and
Reaction product of 3-(2-vinyloxyethoxy)propylene-1,2-carbonate and acrylic acid: 
The acetal-linked propylene carbonate functional (meth)acrylic ester compounds of the invention may be used as reactive diluents in conventional polymer-forming compositions based on free-radically polymerizable ethylenically unsaturated compounds. They are low viscosity monomers with excellent solubilizing properties and very high reactivity in free radical polymerization and copolymerization reactions. They may be employed as neat monomers (i.e. 100%) but more typically they may be used to modify (meth)acrylate-based formulations as additives that are effective at levels ranging from about 1% to about 90% or more, typically at levels ranging from about 5% to about 50% by weight of the total composition. The amount employed will depend on the particular formulation used, the desired rheology and reactivity of the modified formulation and on the final properties of the cured material.
The new monomers are compatible with radiation, anaerobic and 2-part structural adhesive cure systems. Although mono-functional in (meth)acrylate, the monomers cure to give crosslinked, insoluble polymers and copolymers.
As mentioned, curable formulations of the invention will typically include one or more other free-radically polymerizable ethylenically unsaturated compounds, in addition to the inventive monomers. Such compounds include a wide variety of materials represented by (H2Cxe2x95x90CR4C(xe2x95x90O)Q)nR5, where R4 may be hydrogen, halogen or alkyl of 1 to about 4 carbon atoms, Q is O, NH or NCH3, n is a positive number of at least 1 and R5 is any n-valent organic group. R5 may be, for instance, alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkaryl, aralkyl or aryl groups of 1 to about 16 carbon atoms, any of which may be optionally substituted or interrupted as the case may be with silane, silicon, oxygen, halogen, carbonyl, hydroxyl, ester, carboxylic acid, urea, urethane, carbamate, amine, amide, sulfur, sulfonate, sulfone and the like.
The inventive monomer compounds may be employed in an amount of about 1% to about 99% by weight of the composition, more typically from about 10% to about 70%, and especially from 20% to about 50% by weight of the composition. The other free-radically polymerizable ethylenically unsaturated compounds may be employed in an amount of about 1% to about 99% by weight of the composition, more typically from about 5% to about 85%, and especially from 10% to about 60% by weight of the composition.
Suitable (meth)acrylate monomers which may be included as other free-radically polymerizable ethylenically unsaturated compounds in the compositions of the invention are, for instance, mono, di, or poly(meth)acrylate compounds, including various prepolymer compounds such as urethane acrylates and epoxy acrylates, and oligomers. Examples include xcex2-carboxyethyl acrylate, isopropyl acrylate, ethyl acrylate, propyl acrylate, n-octyl acrylate, n-decyl acrylate, cyclohexyl acrylate, tetrahydrofurfuryl acrylate, 2-ethylhexyl acrylate, ethoxyethoxyethyl acrylate, ethoxylated phenyl monoacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, isooctyl acrylate, n-butyl acrylate, isobutyl acrylate, neopentyl glycol diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, dipropylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, 1,6-hexane diol diacrylate, tripropylene glycol diacrylate, glycerol triacrylate, trimethylol propane diacrylate, trimethylol propane triacrylate, pentaerythritol tetraacrylate, phenoxyethyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, cyclohexyl methacrylate, glycerol mono-methacrylate, glycerol 1,3-dimethacrylate, trimethylcyclohexyl methacrylate, methyl triglycol methacrylate, isobornyl methacrylate, trimethylolpropane trimethacrylate, neopentyl glycol dimethacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, 1,6- hexanediol dimethacrylate, hydroxybutyl methacrylate, tetrahydrofurfuryl methacrylate, phenoxyethyl methacrylate, polyethylene glycol dimethacrylate and so forth. Other (meth)acrylate compounds which may be included in the inventive compositions include polyethylene glycol di(meth)acrylates, bisphenol-A di(meth)acrylates, such as ethoxylated bisphenol-A methacrylate (xe2x80x9cEBIPMAxe2x80x9d) and tetrahydrofuran (meth)acrylates and di(meth)acrylates, ethoxylated trimethylol propane tri(meth)acrylates, (meth)acrylated polyesters, (meth)acrylated polyethers, (meth)acrylate capped urethane compounds and combinations thereof.
Further monomers, prepolymer and oligomer compounds having olefinically unsaturated functional groups co-curable with (meth)acrylate compounds, for instance vinyl acylate monomers, diene monomers, stryryl functional monomers, (meth)acrylamido functional monomers, corresponding prepolymer compounds and oligomers, and the like, may also be included in the compositions of the invention.
The curable compositions may be coating, adhesive or sealant compositions. Many such formulations are commercially available or described in the art, and may be beneficially modified by inclusion of the inventive monomer compositions.
The curable compositions are suitably formulated with a free radical initiator, although in some cases they may be curable, e.g. by irradiation without including an initiator compound.
For compositions which are desired to be photocuring a photoinitiator component will typically be included. The photoinitiators are suitably active in the UV/visible range, approximately 250-850 nm, or some segment thereof. Examples of photoinitiators, which initiate under a free radical mechanism, include benzophenone, acetophenone, chlorinated acetophenone, dialkoxyacetophenones, dialkylhydroxyacetophenones, dialkylhydroxyacetophenone esters, benzoin, benzoin acetate, benzoin alkyl ethers, dimethoxybenzoin, dibenzylketone, benzoylcyclohexanol and other aromatic ketones, acyloxime esters, acylphosphine oxides, acylphosphosphonates, ketosulfides, dibenzoyldisulphides, diphenyldithiocarbonate and diphenyl(2,4,6-trimethylbenzoyl) phosphine oxide. The photoinitiators that may be used in the adhesive compositions of the present invention include photoinitiators available commercially from Ciba-Geigy Corp., Tarrytown, N.Y. under the xe2x80x9cIRGACURExe2x80x9d and xe2x80x9cDAROCURxe2x80x9d tradenames, specifically xe2x80x9cIRGACURExe2x80x9d 184 (1-hydroxycyclohexyl phenyl ketone), 907 (2-methyl-1-[4-(methylthio)phenyl]-2-morpholino propan-1-one), 369 (2-benzyl-2-N,N-dimethylamino-1-(4-morpholinophenyl)-1-butanone), 500 (the combination of 1-hydroxy cyclohexyl phenyl ketone and benzophenone), 651 (2,2-dimethoxy-2-phenyl acetophenone), 1700 (the combination of bis(2,6-dimethoxybenzoyl-2,4-,4-trimethyl pentyl phosphine oxide and 2-hydroxy-2-methyl- 1-phenyl-propan-1-one) and xe2x80x9cDAROCURxe2x80x9d 1173 (2-hydroxy-2-methyl-1-phenyl-1-propane) and 4265 (the combination of 2,4,6-trimethylbenzoyldiphenyl-phosphine oxide and 2-hydroxy-2-methyl-1-phenyl-propan-1-one); photoinitiators available commercially from Union Carbide Chemicals and Plastics Co. Inc., Danbury, Conn. under the xe2x80x9cCYRACURExe2x80x9d tradename, such as xe2x80x9cCYRACURExe2x80x9d UVI-6974 (mixed triaryl sulfonium hexafluoroantimonate salts) and UVI-6990 (mixed triaryl sulfonium hexafluorophosphate salts); and the visible light [blue] photoinitiators, d1-camphorquinone and xe2x80x9cIRGACURExe2x80x9d 784DC. Of course, combinations of these materials may also be employed herein.
Photoinitiators particularly suitable for use herein include ultraviolet photoinitiators, such as 2,2-dimethoxy-2-phenyl acetophenone (e.g., xe2x80x9cIRGACURExe2x80x9d 651), and 2-hydroxy-2-methyl-1-phenyl-1-propane (e.g., xe2x80x9cDAROCURxe2x80x9d 1173) and the ultraviolet/visible photoinitiator combination of bis(2,6-dimethoxybenzoyl-2,4,4-trimethylpentyl) phosphine oxide and 2-hydroxy-2-methyl-1-phenyl-propan-1-one (e.g., xe2x80x9cIRGACURExe2x80x9d 1700), as well as the visible photoinitiator bis(xcex75-2,4-cyclopentadien-1-yl)-bis[2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl]titanium (e.g., xe2x80x9cIRGACURExe2x80x9d 784DC). xe2x80x9cLUCIRINxe2x80x9d TPO, from BASF is another preferred photoinitiator.
Typically, the photoinitiators will be employed in an amount of 0.1 to 10%, suitably 0.5 to 7% and especially from about 1 to about 5% by weight of the composition.
The photocuring compositions of the invention may be cured by transmitting energy to the composition which is effective to activate the photoinitiator, suitably by irradiation, typically with UV or visible light. Irradiation of substrates treated in accordance with the practice of the invention can be achieved by the use of UV lamps such as mercury arc lamps (high, medium and low pressure), xenon arc lamps, high intensity halogen-tungsten arc lamps, microwave driven arc lamps and lasers. Additional means of irradiation which can be used are, for example, x-rays, ionizing irradiation using 60Co xcex3-rays and electron beam irradiation. In some cases the compositions may also be curable by heat or by IR irradiation.
Additionally or alternatively to a photoinitiator, the curable formulations of the present invention may include a peroxide, azonitrile or other thermally activated free-radical initiator, including within this category anaerobically curing ambient temperature initiator systems which are well known in the art of curable (meth)acrylate compositions. Typical curing agents are hydroperoxides, for example, t-butyl hydroperoxide, p-methane hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, and the like. Typically, thermally activated initiators will be employed in an amount of 0.1 to 10%, suitably 1 to 5% by weight of the composition.
An accelerator may be included, particularly if the composition is curable by an anaerobic curing mechanism. Typical accelerators include amines, amine oxides, sulfonamides, metal sources, acids and/or triazines, for example, ethanol amine, diethanol amine, triethanol amine, N,N dimethyl aniline, benzene sulphonimide, cyclohexyl amine, triethyl amine, butyl amine, saccharin, N,N-diethyl-p-toluidine, N,N-dimethyl-o-toluidine, acetyl phenylhydrazine, maleic acid and the like. Of course, other materials known to induce anaerobic cure may also be included or substituted therefor. See e.g., U.S. Pat. No. 3,218,305 (Krieble), U.S. Pat. No. 4,180,640 (Melody), U.S. Pat. No. 4,287,330 (Rich) and U.S. Pat. No. 4,321,349 (Rich). Typically, accelerators will be employed in an amount of 0.1 to 10%, suitably 0.5 to 5% by weight of the composition.
The cyclic carbonate group in the inventive compounds provides an additional cross-linking site by an optional secondary cure mechanism. Exemplary of such a secondary mechanism are ring-opening addition reactions with multi-amine and multicarboxylic acid curing agents. The new monomers may also be polymerized through the cyclic carbonate group (with cationic or anionic catalysts) to give acyclic polycarbonates that show little or no shrinkage on polymerization.
To facilitate curing through propylene carbonate polymerization the photoinitiator component may be, or may include, a cationic photoinitiator. Suitable cationic photoinitiators are onium salts represented by the general formula:
xe2x80x83[R6xe2x88x92A+][X!]
where R6 is an aromatic radical, for instance aryl, alkaryl, and aralkyl groups, including fused ring structures comprising an aromatic ring, which may be optionally substituted with a linear, branched or cyclic C8 to C20 radical of alkyl, alkylene, alkoxy alkyleneoxy, a nitrogen, oxygen or sulfur heterocyclic radical of 4 to 6 carbon atoms in the ring; or a mixture thereof, A+ is selected from the group of iodonium cation mono-substituted with C1 to C20 alkyl or aryl optionally substituted with C1 to C20 alkyl or alkoxy and sulfonium cation di-substituted with C1 to C20 alkyl or aryl optionally substituted with C1 to C20 alkyl or alkoxy or a mixture thereof and Xxe2x88x92 is a non-basic, non-nucleophilic anion, examples of which include SbF6xe2x88x92, AsF6xe2x88x92, PF6xe2x88x92, BF4xe2x88x92, ClO4xe2x88x92, CF3SO3xe2x88x92 and the like. Examples of such cationic photoinitiators are diaryliodonium, triarylsulfonium, diaryliodosonium, triarylsulfoxonium, dialkylphenacylsulfonium and alkylhydroxyphenylsulfonium salts. Syntheses of such onium salts are described in U.S. Pat. No. 4,219,654 (Crivello); U.S. Pat. No. 4,058,400 (Crivello); U.S. Pat. No. 4,058,401 (Crivello) and U.S. Pat. No. 5,079,378 (Crivello). Although various members of the series of onium salts indicated above may be used in the practice of this invention, those bearing the SbF6! anion are preferred. Commercial aryl onium salt cationic photoinitiators include UVI-6974, from Dow Chemical and UVE 1014 and UVE 1016 from General Electric Co.
Other suitable cationic photoinitiators include xcex75,xcex76-iron arene complex salt catalysts as described in U.S. Pat. No. 4,808,638 (Steinkraus et al) at cols 5-6. These catalysts, characterized as xe2x80x9cferrocenium saltxe2x80x9d catalysts include, for instance IRGACURE 261 [xcex75-2,4-cyclopentadien-1-yl][(1,2,3,4,5,6-xcex7)(1-methyl ethyl)benzene]-iron (+)-hexafluorophosphate (xe2x88x92), sold by Ciba Speciality Chemicals.
In compositions comprising cationic photoinitiator compounds the inventive monomers may have particular advantage in improving solubility of the cationic photoinitiator component in the overall composition.
In connection with the secondary cure mechanism provided by the inventive monomer compounds, curable compositions of the invention may be formulated with other compounds co-curable the inventive compounds by such secondary cure mechanism. Examples of such other compounds include epoxy, vinyl ether, styryloxy and polythiols.
The compositions of the invention may also include an inhibitor of polymerization in an amount effective to give desired shelf stability to the composition. Suitable inhibitors are well known to those skilled in the art and include those described in the aforementioned patents which described anaerobic compositions. Metal chelators, such as ethylenediamine tetraacetate (xe2x80x9cEDTAxe2x80x9d), or salts thereof, and 1-hydroxyethylidine-1,1-diphosphonic acid (xe2x80x9cHEDPAxe2x80x9d), and quinone type inhibitors, such as hydroquinone, methyl hydroquinone, napthoquinone, anthraquinone and benzoquinone, as well as BHT (butylated hydroxy toluene), are exemplary. Such inhibitors are typically employed at a level of 0.1-1.0% by weight of the composition.
Various adhesion promoters may be used in the curable compositions of the invention. Adhesion promoters may include acid functional monomers such as acrylic acid or methacrylic acid, and silane adhesion promoters such as glycidoxypropyltrimethoxysilane, methacryloxypropyltrimethoxysilane, methacryloxypropyltriacetoxysilane, and acryloxypropyltrimethoxysilane, and various unsaturated nitrogen-containing compounds such as N,Nxe2x80x2-dimethylacrylamide, acryloyl morpholine, and the adhesion promoters described in International Patent Publication No. WO 00/40663, for instance N-methyl-N-vinyl acetamide, N-vinyl caprolactam, N-vinylphthalimide, Uracil, and N-vinylpyrrolidone. Adhesion promoters may be used alone or in combination. The adhesion promoter or promoters may suitably be employed in the curable formulations in an amount from about 0.5% to about 30% by weight of the composition, more typically 1% to about 20% by weight, and particularly about 2% to about 10% by weight.
The compositions of the invention may also include an elastomeric polymer toughener, or mixture thereof. The toughening polymer will typically, but always be a block copolymer, including terpolymer, with a Tg of one block segment below xe2x88x9220xc2x0 C. Suitably the elastomeric polymer is one which is dissolvable or highly swellable in the vinyl ether or propenyl ether monomer utilized in the formulation. Examples of suitable polymer tougheners include acrylic rubbers, butadiene/acrylonitrile rubber, styrene/butadiene rubber, buna rubber, polyisobutylene, polyisoprene, natural rubber, polyurethane rubbers, ethylenevinyl acetate polymers, fluorinated rubbers, isoprene-acrylonitrile polymers, chlorosulfonated polyethylenes, homopolymers of polyvinyl acetate, etc. Preferred polymer tougheners include acrylic rubbers and millable polyurethane rubbers.
The amount of toughener can be varied to suit particular applications. A high level of toughener increases the viscosity of the resulting composition. The concentration range of elastomeric polymer will suitably be from about 3 to about 50 percent by weight, preferably 5 to about 30 percent, and more preferably about 7 to about 25% based on the weight of the composition. Mixtures of tougheners can be used if desired.
In addition to the composition components described above, the compositions may also include non-elastomeric polymers such as poly(methyl methacrylate), polystyrene, poly-xcex1-methylstyrene, polyacenaphthalene, polyindene, polyphenols, and novolac resins. Inorganic fillers such as silica, talc, clay, barytes, hydrated alumina and glass, polyolefin or polyimide fibers may also be included to provide desirable mechanical characteristics, provided that they are not supplied in sufficient amount to preclude sufficient light penetration to the desired cure depth to effect cure initiation within a reasonable irradiation time.
The inventive compositions may also optionally contain other conventional additives e.g. to regulate storage stability, viscosity, surface wetting properties, to promote adhesion, and the like. The formulation may be provided with a colorant, fluorescent agent or phosphorescent agent, for instance, to facilitate inspection of the applied composition prior to curing.
Examples specific applications where the inventive monomers provide beneficial results include as diluents in photocurable DVD bonding formulations, panel-bonding formulations and specialty coatings, and in electronics as a precursor of latent fluxing agents and for high-dielectric coatings.